A virtual circuit (VC) is a network connection that appears to the user to be set aside solely for him, even though in actuality the physical link may be shared with many other users. One termination point of a virtual circuit is typically a router controlled by the Internet Service Provider (ISP) granting access to the user.
Digital Subscriber Line (DSL) technology has been growing in popularity as an alternative to slower Internet connections, such as dial-up access, and as an alternative to expensive and high-maintenance faster Internet connections, such as T1 lines. FIG. 1 is a diagram illustrating a typical DSL system. A user 100 may connect via Customer Premises Equipment (CPE) 102, such as a DSL modem, to a Digital Subscriber Line Access Multiplexor (DSLAM) 104. The DSLAM 104 may aggregate many different physical connections (such as from other users 106, 108) into a single physical line 110, which terminates at a router or gateway 112.
It is common practice for each user 100 to be assigned a separate virtual circuit (VC), such as by using an Asynchronous Transfer Mode (ATM) VC. Thus, while there is only one physical line 110 between the DSLAM 104 and the router 112, there may be many virtual circuits.
Traditionally, this router 112 may be configured to receive virtual circuits by manually configuring each virtual circuit as it is brought up (to the point where it is recognized by the router-configuring additional parameters is a separate issue). While this may work fine for instances where many subscribers can share the same VC (resulting in a small number of VC's to be configured on the router) such as in the Level 2 Tunneling Protocol (L2DP), in the DSL world, where each VC represents a single subscriber, this manual configuration may be extremely time consuming. It is not unusual for a single router to manage 8,000 or more subscribers at once. Obviously, configuring each virtual circuit manually as it is brought up requires significant effort, and can result in an unwieldy configuration file.
When a virtual circuit is brought up, typically information regarding the virtual circuit must be passed from the DSLAM 104 to the router 112. Since often these components are operated by separate companies, the information is usually passed via e-mail or voice communication, and then manually configured on the router side. The information typically comprises a virtual circuit number, which must be unique and must be the same on both ends. It also comprises the type of ATM VC to be used, such as Unspecified Bit Rate (UBR), Variable Bit Rate (VBR), and Committed Bit Rate (CBR), a Quality of Service (QoS) level, indicating the amount of bandwidth to allocate to the VC, and whether packets on the circuit will be snap-encapsulated or MUX encapsulated. Although it is often necessary to inform the router of all this information, it is not necessary that all be transmitted. Certain “packages” may be set up such that only the name of the package need to be identified, such as “gold” for the best package, along with the VC number. Nevertheless, each VC must still be manually configured on the router.
One potential solution to this problem would be to preconfigure a range of virtual circuits. A standard package could be assumed and the router could, for example, set up a range of a hundred VCs, even though user's have not been assigned to the VCs yet. The problem with this, however, is that the range is contiguous and VCs typically aren't assigned in a strict order.
Another potential solution would be to use the Interim Local Management Interface (ILMI) protocol. ILMI facilitates network-wide auto-configuration by allowing adjacent nodes to determine each other's characteristics. Thus, the router could talk with a DSLAM via ILMI and incorporate all of its VC configuration information. This solution works well if a single enterprise owns both the SLAM and the router. However, as discussed above that is typically not the case, so this solution is not a desirable one.
What is needed is a solution that allows for the provisioning of a large number of subscribers using virtual circuits in a quick, easy, and error-free way.